Novel oxyapatite-type Ba2La3(SiO4)2(PO4)O:Eu3+ phosphors for high-CRI LED lighting and fingerprint visualization with level III details

A series of novel single-phase oxyapatite-type Eu 3+ -doped Ba 2 La 3 (SiO 4 ) 2 (PO 4 )O (BLSPO) phosphors for the first time were synthesized by means of a high-temperature solid-state reaction. The prepared phosphors were analyzed in terms of phase purity using X-ray diffraction (XRD) and Rietveld refinement. The BLSPO:Eu 3+ phosphors pertain to the hexagonal crystal structure and the P 6 3 / m (No.176) space group. BLSPO as an indirect bandgap semiconductor, has been experimentally determined to possess a bandgap energy of 4.85 eV, while theoretical calculations yield a value of 4.45 eV. The photoluminescence excitation of BLSPO:Eu 3+ exhibits the highest peak at 393 nm. Four distinct characteristic peaks are observed in the emission spectrum of BLSPO:Eu 3+ . Notably, the peak at 618 nm shows the highest emission intensity due to the radiative transition from 5 D 0 - 7 F 2 . By varying doping concentrations, it was determined that an optimal concentration of 0.30 mol Eu 3+ resulted in phosphors, with high color purity up to 100 %. At 420 K, the emission intensity of the BLSPO:0.30Eu 3+ phosphor can still maintain 66.8 % of the starting intensity observed at 300 K. The internal quantum efficiency (IQE) of BLSPO:0.30Eu 3+ is 74.7 %. The Commission International de L'Eclairage (CIE) color coordinate of w-LED was measured as (0.328, 0.334), correlating to correlated color temperature (CCT) of 5706 K and exhibiting a good color rendering index (CRI, R a  = 92). Additionally, the BLSPO:0.30Eu 3+ phosphor surface was functionalized with oleic acid (OA) (BLSPO:0.30Eu 3+ @OA) to help identify fingerprint details at levels I-III details with high contrast and high resolution. Excellent visualization of latent fingerprints (LFPs) was observed on different substrates. In conclusion, high-efficiency oxyapatite-based BLSPO:Eu 3+ phosphors have attractive potential for w-LED and LFP applications.